Field of the Invention
This invention relates to medical syringes. More specifically, the invention is directed to a locking device having a winged retaining member which completely engages all sides of finger grips on the syringe.
There are many devices developed to lock a movable plunger of a syringe in a certain position so that the syringe can be controlled. For example, U.S. Pat. No. 3,890,971 to Lesson et al. describes an one-time syringe having a permanently locking plunger by dents to prevent reuse. U.S. Pat. No. 4,386,606 to Tretinyak et al. discloses a syringe with a barrel and plunger. The plunger is removable along the axis of the barrel and lockable by a locking means. The locking means includes a cam member which when moved into a position forces the plunger into binding contact with the barrel. U.S. Pat. No. 4,610,672 to Ewalt et al. describes a locking device attached to the finger grips of a syringe and includes an aperture aligned with the longitudinal axis of the barrel. The aperture includes two ridges extending chordally across the circular opening wherein the ridges engage the plunger when oriented in one position. U.S. Pat. No. 4,874,385 to Moran et al. describes a movable locking member which is capable of moving axially on the plunger and can be placed in a fixed condition to limit movement of the plunger. U.S. Pat. No. 4,890,626 to Wang discusses a syringe plunger stop and lock attachment wherein the plunger is specifically designed with grooves at predetermined distances such that the stop member will engage the plunger and prevent axially movement of the plunger.
Each of these stopping or locking devices either require modifications of the plunger or syringe, addition of a separate camming means, or do not securely fit the finger grips of the syringe and thus shift or slide when in use.
Accordingly, the medical locking devices exemplified in the patents referred to hereinabove illustrate the many improvements made over the years in simplifying and improving this aspect of syringes. There still exists, however, in this industry, a need for a medical locking device which absolutely prevents and movement of the plunger as well as shifting of the locking device once locked in a manner that particularly improves the safety, efficiency and economics of the syringes with locking devices, and simplifies installation, operation and maneuverability.